In architecture, Alexander's work is used by a number of different contemporary architectural communities of practice, including the New Urbanist movement, to help people to reclaim control over their own built environment.[9] However, Alexander is controversial among some mainstream architects and critics, in part because his work is often harshly critical of much of contemporary architectural theory and practice.[10]

Alexander is known for his many books on the design and building process, including Notes on the Synthesis of Form, A City is Not a Tree (first published as a paper and recently re-published in book form), The Timeless Way of Building, A New Theory of Urban Design, and The Oregon Experiment. More recently he published the four-volume The Nature of Order: An Essay on the Art of Building and the Nature of the Universe, about his newer theories of "morphogenetic" processes, and The Battle for the Life and Beauty of the Earth, about the implementation of his theories in a large building project in Japan.

Alexander is perhaps best known for his 1977 book A Pattern Language, a perennial seller some four decades after publication.[11] Reasoning that users are more sensitive to their needs than any architect could be,[12][13][14] he produced and validated (in collaboration with his students Sara Ishikawa, Murray Silverstein, Max Jacobson, Ingrid King, and Shlomo Angel) a "pattern language" to empower anyone to design and build at any scale.

As a young child Alexander emigrated in fall 1938[15] with his parents from Austria to England, when his parents were forced to flee the Nazi regime. He spent much of his childhood in Chichester and Oxford, England, where he began his education in the sciences. He moved from England to the United States in 1958 to study at Harvard University and Massachusetts Institute of Technology. He moved to Berkeley, California in 1963 to accept an appointment as Professor of Architecture, a position he would hold for almost 40 years. In 2002, after his retirement, Alexander moved to Arundel, England, where he continued to write, teach and build. Alexander is married to Margaret Moore Alexander, and he has two daughters, Sophie and Lily, by his former wife Pamela.

Alexander attended Oundle school, England. In 1954, he was awarded the top open scholarship to Trinity College, Cambridge University in chemistry and physics, and went on to read mathematics. He earned a Bachelor's degree in Architecture and a Master's degree in Mathematics. He took his doctorate at Harvard (the first Ph.D. in Architecture ever awarded at Harvard University), and was elected fellow at Harvard. During the same period he worked at MIT in transportation theory and computer science, and worked at Harvard in cognition and cognitive studies.

There is one timeless way of building. It is a thousand years old, and the same today as it has ever been. The great traditional buildings of the past, the villages and tents and temples in which man feels at home, have always been made by people who were very close to the center of this way. It is not possible to make great buildings, or great towns, beautiful places, places where you feel yourself, places where you feel alive, except by following this way. And, as you will see, this way will lead anyone who looks for it to buildings which are themselves as ancient in their form, as the trees and hills, and as our faces are.

The work originated from an observation that many medieval cities are attractive and harmonious. The authors said that this occurs because they were built to local regulations that required specific features, but freed the architect to adapt them to particular situations.

The book provides rules and pictures, and leaves decisions to be taken from the precise environment of the project. It describes exact methods for constructing practical, safe and attractive designs at every scale, from entire regions, through cities, neighborhoods, gardens, buildings, rooms, built-in furniture, and fixtures down to the level of doorknobs.

A notable value is that the architectural system consists only of classic patterns tested in the real world and reviewed by multiple architects for beauty and practicality.

The book includes all needed surveying and structural calculations, and a novel simplified building system that copes with regional shortages of wood and steel, uses easily stored inexpensive materials, and produces long-lasting classic buildings with small amounts of materials, design and labor. It first has users prototype a structure on-site in temporary materials. Once accepted, these are finished by filling them with very-low-density concrete. It uses vaulted construction to build as high as three stories, permitting very high densities.

This book's method was adopted by the University of Oregon, as described in The Oregon Experiment (1975), and remains the official planning instrument. It has also been adopted in part by some cities as a building code.

The idea of a pattern language appears to apply to any complex engineering task, and has been applied to some of them. It has been especially influential in software engineering where patterns have been used to document collective knowledge in the field.

A New Theory of Urban Design (1987) coincided with a renewal of interest in urbanism among architects, but stood apart from most other expressions of this by assuming a distinctly anti-masterplanning stance. An account of a design studio conducted with Berkeley students, it shows how convincing urban networks can be generated by requiring individual actors to respect only local rules, in relation to neighbours. A vastly undervalued part of the Alexander canon, A New Theory is important in understanding the generative processes which give rise to the shanty towns latterly championed by Stewart Brand,[18]Robert Neuwirth,[19] and the Prince of Wales.[20]

The Nature of Order: An Essay on the Art of Building and the Nature of the Universe (2003–04), which includes The Phenomenon of Life, The Process of Creating Life, A Vision of a Living World and The Luminous Ground, is Alexander's most comprehensive and elaborate work. In it, he puts forth a new theory about the nature of space and describes how this theory influences thinking about architecture, building, planning, and the way in which we view the world in general. The mostly static patterns from A Pattern Language have been amended by more dynamic sequences, which describe how to work towards patterns (which can roughly be seen as the end result of sequences). Sequences, like patterns, promise to be tools of wider scope than building (just as his theory of space goes beyond architecture).

The online publication Katarxis 3 (September 2004) includes several essays by Christopher Alexander, as well as the legendary debate between Alexander and Peter Eisenman from 1982.[21]

Alexander's latest book, The Battle for the Life and Beauty of the Earth: A Struggle Between Two World-Systems (2012), is the story of the largest project he and his colleagues had ever tackled, the construction of a new High School/College campus in Japan. He also uses the project to connect with themes in his four-volume series. He contrasts his approach, (System A) with the construction processes endemic in the US and Japanese economies (System B). As Alexander describes it, System A is focused on enhancing the life/spirit of spaces within given constraints (land, budget, client needs, etc.) (drawings are sketches - decisions on placing buildings, materials used, finish and such are made in the field as construction proceeds, with adjustments as needed to meet overall budget); System B ignores, and tends to diminish or destroy that quality (architect responsible for drawings which the builder uses to build structures at the lowest possible cost). In the last few chapters he describes "centers" as a way of thinking about the connections among spaces, and about what brings more wholeness and life to a space.

Among Alexander's most notable built works are the Eishin Campus near Tokyo (the building process of which is outlined in his 2012 book The Battle for the Life and Beauty of the Earth); the West Dean Visitors Centre [22] in West Sussex, England; the Julian Street Inn (a homeless shelter) in San Jose, California (both described in Nature of Order); the Sala House and the Martinez House (experimental houses in Albany and Martinez, California made of lightweight concrete); the low-cost housing in Mexicali, Mexico (described in The Production of Houses); and several private houses (described and illustrated in The Nature of Order). Alexander's built work is characterized by a special quality (which he used to call "the quality without a name", but named "wholeness" in Nature of Order) that relates to human beings and induces feelings of belonging to the place and structure. This quality is found in the most loved traditional and historic buildings and urban spaces, and is precisely what Alexander has tried to capture with his sophisticated mathematical design theories. Paradoxically, achieving this connective human quality has also moved his buildings away from the abstract imageability valued in contemporary architecture, and this is one reason why his buildings are under-appreciated at present.[10]

His former student and colleague Michael Mehaffy wrote an introductory essay on Alexander's built work in the online publication Katarxis 3, which includes a gallery of Alexander's major built projects through September 2004.[23]

In addition to his lengthy teaching career at Berkeley (during which a number of international students began to appreciate and apply his methods), Alexander was a key faculty member at both The Prince of Wales's Summer Schools in Civil Architecture (1990–1994) and The Prince's Foundation for the Built Environment.[20]

Alexander's work has widely influenced architects; among those who acknowledge his influence are Sarah Susanka,[24]Andres Duany,[25] and Witold Rybczynski.[26]Robert Campbell, the Pulitzer Prize-winning architecture critic for the Boston Globe, stated that Alexander "has had an enormous critical influence on my life and work, and I think that's true of a whole generation of people."[26]

Architecture critic Peter Buchanan, in an essay for The Architectural Review's 2012 campaign The Big Rethink, argues that Alexander's work as reflected in A Pattern Language is "thoroughly subversive and forward looking rather than regressive, as so many misunderstand it to be." He continues:

Even architects not immune to the charms of the places depicted, are loath to pursue the folksy aesthetic they see as implied and do not want to engage with such primitive construction – although the systemic collapse now unfolding may force that upon them. The daunting challenge for architects then, if such a thing is even possible to realise, would be to recreate in a more contemporary idiom both the richness and quality of experience suggested by the pattern language.[27]

Many urban development projects continue to incorporate Alexander's ideas. For example, in the UK the developers Living Villages have been highly influenced by Alexander's work and used A Pattern Language as the basis for the design of The Wintles in Bishops Castle, Shropshire.[28]Sarah Susanka's "Not So Big House" movement adapts and popularizes Alexander's patterns and outlook.

Alexander has often led his own software research, such as the 1996 Gatemaker project with Greg Bryant.[35][36]

Alexander discovered and conceived a recursive structure, so called wholeness, which is defined mathematically, exists in space and matter physically, and reflects in our minds and cognition psychologically. He had his idea of wholeness back to early 1980s when he finished his very first version of The Nature of Order. In fact, his idea of wholeness or degree of wholeness relying a recursive structure of centers resemble in spirit to Google's PageRank.[37]

The fourth volume of The Nature of Order approaches religious questions from a scientific and philosophical rather than mystical direction. In it, Alexander describes deep ties between the nature of matter, human perception of the universe, and the geometries people construct in buildings, cities, and artifacts. He suggests a crucial link between traditional practices and beliefs, and recent scientific advances.[38] Despite his leanings toward Deism, and his naturalistic and anthropological approach to religion, Alexander maintains that he is a practicing member of the Catholic Church, believing it to embody a great deal of accumulated human truth within its rituals.[39]

The life's work of Alexander is dedicated to turn design from unselfconscious behavior to selfconscious behavior, so called design science. In his very first book Notes on the Synthesis of Forms, he has set what he wanted to do. He was inspired by traditional buildings, and tried to derive some 253 patterns for architectural design. Later on, we further distill 15 geometric properties to characterize living structure in The Nature of Order. The design principles are differentiation and adaptation.